1. Technical Field of the Invention
The present invention relates to a leader tape, a cutting method for a leading end of a leader tape, and a magnetic tape cartridge. More specifically, the invention relates to a processing of a leading end of a leader tape for strongly splicing the leader tape onto a magnetic tape wound around a single reel in a magnetic tape cartridge, and to a cutting method for the leading end to achieve the processing.
2. Description of the Related Art
As a magnetic tape cartridge used as a recording medium for a computer or the like, there has been known a magnetic cartridge configured such that a single reel, around which a magnetic tape is wound, is rotatably stored in a cartridge case constructed of an upper cartridge half and a lower cartridge half.
When in use, the magnetic tape cartridge is used such that a magnetic tape is drawn out through an opening of the cartridge case. When the magnetic tape cartridge is not in use, in a state that the magnetic tape is completely wound around a reel, a leader tape (engagement means which is engaged to engagement means disposed in a device, such as a computer, for guiding the magnetic tape to a tape path of the device) which is spliced to one end of the magnetic tape is fixed to an end face of a cartridge case and also fixed by locking means such as a reel lock so as to prevent unexpected rotation. The opening is closed by a lid which is attached openable and closable.
FIG. 6 is a side view showing a state where a leader tape is spliced onto one end of a magnetic tape. As shown in FIG. 6, one end of the magnetic tape 60 is spliced to the leader tape 62 made from polyethylene terephthalate (PET) by means of a splicing tape 64. The leader tape 62 has a thickness “t” when in a state of a material tape, which is a state before being subjected to predetermined processing; however, a taper processing of tapering down the thickness “t” is performed on a section 62a on the side close to the magnetic tape 60 so as to assure splicing to the magnetic tape 60 by means of the splicing tape 64. Since a remarkable step is not formed on a splicing section between the leader tape 62 and the magnetic tape 60 by virtue of the tapered section, stable running of the magnetic tape is also enabled.
Meanwhile, two methods have hitherto been proposed for application of a taper processing to a PET material tape having the thickness “t” to thus manufacture the leader tape 62.
One is a method to process the tapered section through chemical processing by means of etching, and the other is a method to process the tapered section through mechanical cutting.
The former chemical processing by means of etching is advantageous in that the finished surface is free from roughness, and free from fear that a cutting burr protrudes out from an end of the leader tape. However, since the chemical processing requires processes, such as chemical coating, cleaning, and drying, time required for the processing becomes long. In addition, inclusion of the plurality of processes results in decrease in productivity. Furthermore, high cost in the chemical processing has resulted in a cost increase.
The second method of mechanical cutting is performed such that, as described in JP-A-2000-11591, a leading end of a leader tape is mechanically cut to a tapered shape by means of rotating a cylindrical end mill in a state inclined at a certain angle in relation to a rotation axis of the roller.
FIG. 7 is a view showing a metal roller and an end mill performing the mechanical cut method described in JP-A-2000-11591. In the drawing, reference numeral 140 denotes a material tape, 140a indicated by a hatched pattern denotes a to-be-cut section, 142 denotes a metal roller, and 143 denotes a cylindrical end mill.
As shown in the drawing, the to-be-cut section 140a indicated by a hatch pattern is mechanically cut to a tapered shape by the cylindrical end mill 143; and a rotation axis of the end mill 143 is not parallel to a rotation axis of the metal roller 142 but is inclined by a certain angle. By means of setting the angle appropriately and moving the end mill 143 in the direction for the material tape, the to-be-cut section 140a on the material tape 140 can be taper-cut by a desired amount.
As described above, processing of the tapered section on the material tape (i.e., the leader tape) 140 by a mechanical method is advantageous in that time required for processing can be shortened and cost can be reduced in comparison with a taper processing by means of chemical processing.
However, a leader tape obtained with use of such a general cutting technique has a surface roughness RZ which is as large as 8 μm or more (RZ complies with JIS B0601-1994). The inventor has realized that this surface roughness may result in protrusion of a cutting burr or the like from an end of the leader tape, and the thus-protruding cutting burr will come off by being scratched, thereby rendering harm to other components.